Ignition of rocket thrust devices



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defed maul Shaped charge I ENTOR. Sammy d porfer ECKHOFF 7 SLICK Nov. 8, 1960 5. J. PORTER IGNITION 0F ROCKET THRUST DEVICES 3 Sheets-Sheet 3 Filed Oct. 9, 1957 aluminum or of/Ier mefa/ W am, n w v 7 INVENTOR. Samue/ J. Par-fer E CAHOF'F es s -g g 4 41. lifi A MEMBER OF THE F! United States Patent Samuel J. Porter, Scituate, Mass., assignor to American Potash & Chemical Corporation, a corporation of Delaware Filed Oct. 9, 1957, Ser. No. 689,147

'5 Claims. (Cl. 6035.6)

This invention relates to improvements in the ignition of solid propellants such as are employed in rocket, Jato and related devices.

As improvements have been made in the formulations of solid propellants, the problem of igniting the propellant has become more difiicult. Since it is desirable to ignite all of the burning surface of the propellant in a uniform manner as rapidly as possible, the optimum igniter should produce a large and vigorous discharge of hot gases or particles in a brief time.

I have found that a solid propellant can be effectively ignited by utilizing a combination of a shaped-charge and an ignitable metal, the shaped-charge being effective to fragment, disperse, heat up, vaporize and ignite the metal which, in turn, effects the ignition of the grain of the propellant. The shaped-charge is provided to make use of the Monroe principle. The metal can be utilized in the form of a metallic coating on the grain, a metallic wire or powder distributed around or in close proximity to the grain, a piece of solid metal in the orifice of the shaped-charge, a pellet of compressed metal powder, a readily frangible metal liner for the core of the shapedcharge, or these can be utilized in combination with one another.

It is in general the broad object of the present invention to improve upon the ignition of solid propellants.

The invention includes other objects and features of advantage, some of which, together with the foregoing, will appear hereinafter, wherein the present preferred form of ignition means providing this invention is disclosed. In the drawings accompanying and forming a part hereof, Figures 1, 2, 4 and 5 are side elevations partly in section through typical Jato bottles in which the ignition means characterizing this invention have been incorporated.

Figure 3 is a perspective view, partially broken away, to show in detail the ignition means embodying this invention employed in the assembly of Figure 1.

Referring to the devices shown in Figures 1, 2, 4 and 5, typical Jato configurations are generally indicated at 6, including igniting means 7 provided at one end. The solid propellant is provided between spacers 8 and 9 provided at opposite ends of the chamber 6. A nozzle 11 is provided to receive the gases produced upon ignition of the propellant.

In accordance with this invention, a shaped-charge, generally indicated at 12, is provided at one end of the chamber co-operatively adjacent to the igniter 7. In that form of the invention shown in Figures 1 and 3, a spacer 14 is interposed between the shaped-charge 12 and a mass of powdered metal 16, formed as a cylinder extending coaxially with the shaped-charge. The shapedcharge has a detonator 21 at one end as part of the igniter 7. The charge also includes a conical recess 17 in that end adjacent to the mass of powdered metal 16 so that upon detonation of the shaped-charge, as is shown in the art, it is effective to fragment and vaporize the powdered metal and, simultaneously, to discharge it throughout the central passage 18 extending through the propellant in Figures 1 and 2 where a perforated grain is employed or onto the end surface of the grain as shown in Figures 4 and 5 where the propellant grain has no perforation. Upon detonation, the shaped-charge produces a jet of hot gas and molten or vaporized metal that travels with great rapidity, e.g., in the order of 10,000 to 30,000 feet per second.

In Figure 1 the core 18 is lined with sprayed metallic aluminum or other metal which is readily vaporizable such as magnesium, zirconium, or nickel; in Figure 4 this coating is placed on the grain end. In Figure 5, the entire grain surface of the propellant has been coated with a metal to facilitate the ignition of the grain everywhere on its surface.

In that form of the invention shown in Figure 2, a mass of fine metallic wire 20 is disposed down the central core 18 which is vaporized and projected into the propellant upon ignition of the shaped-charge.

From the foregoing, I believe it will be apparent that I have provided a novel, simple and improved ignition means for solid propellants.

I claim:

1. In a rocket thrust device, a propellant, a combustion chamber confining the propellant and having an outlet nozzle at one end thereof, the propellant having a passage extending therethrough coaxially with the axis of the nozzle and from adjacent the nozzle to the other end of the propellant, a shaped charge provided at the other end of the propellant, and a propellant igniter consisting of a metal positioned cooperatively in the passage and adapted upon detonation of the shaped charge to be heated, vaporized, ignited and dispersed through the passage onto the propellant to ignite the propellant.

2. In a rocket thrust device as in claim 1 wherein the metal is provided by a mass of ignitable metal wire provided in the passage.

3. In a rocket thrust device as in claim 1 wherein the metal is provided by a mass of ignitable powdered metal provided between the shaped charge and an end of the passage.

4. In a rocket thrust device as in claim 1 wherein the metal is provided by an ignitable metal tube defining the passage.

5. In a device of the character described, a mass of a solid propellant having the grain thereof uniformly coated throughout said mass with an ignitable metal, a shaped charge positioned at one end of the propellant, and a propellant igniter consisting of a mass of ignitable metal positioned between the shaped charge and one end of the propellant and adapted, upon detonation of the shaped charge, to be fragmented, heated, vaporized, ignited, and impacted onto the metal coated grain of the propellant by the shaped charge and so ignite said propellant.

References Cited in the file of this patent UNITED STATES PATENTS 1,530,692 Paulis Mar. 24, 1925 2,115,608 Brandt Apr. 26, 1938 2,123,691 Burrows et al July 12, 1938 2,132,996 Palrnieri Oct. 11, 1938 2,305,561 Sylvester Dec. 15, 1942 2,434,652 Hickman Jan. 20, 1948 2,447,200 Miller Aug. 17, 1948 2,627,160 MacDonald Feb. 3, 1953 2,776,623 Bonner Jan. 8, 1957 FOREIGN PATENTS 693,164 Great Britain June 24, 1953 

